Generally, a heat generating component, such as a large scale integration circuit, which is a so-called LSI, and a microprocessor, is mounted on a circuit board included in an electronic device. In recent years, the heat generating component has been reduced in size and increased in operation frequency, and thus it tends to generate a larger amount of heat. Accordingly, there has been a demand for an effective solution for cooling the heat generating component.
For example, Patent Literature 1 discloses a cooling structure for an electronic device as shown in FIG. 9. In the cooling structure shown in FIG. 9, an internal closed-structure housing 105 is disposed in a housing 101. The internal housing 105 accommodates a circuit board 102 on which a heat generating component 103 is mounted. An air passage for cooling 115 is formed between one lateral surface of the internal housing 105 and an inner wall surface of the housing 101. The housing 101 has, on both sides thereof in the extending direction of the air passage for cooling 115, an air inlet 111 and an air outlet 112. A fan 113 is provided at the air outlet 112.
There is further provided in the housing 101a heat transfer member 104 with one end being in contact with the heat generating component 103 directly or via the internal housing 105 and the other end being located in the air passage for cooling 115. The heat transfer member 104 transfers the heat generated in the heat generating component 103 to the air flowing through the air passage for cooling 115. Thereby, the heat generating component 103 is cooled.
Patent Literature 2 discloses a cooling structure for an electronic device as shown in FIG. 10. In the cooling structure shown in FIG. 10, a pressing member 207 is disposed on an inner wall surface of a housing 201, and the pressing member 207 is covered with a heat diffusing sheet 206. The pressing member 207 presses the heat diffusing sheet 206 against a heat generating component 203 mounted on a circuit board 202. Thereby, the heat generated in the heat generating component 203 escapes to the inner wall surface of the housing 201 via the heat diffusing sheet 206 and the pressing member 207.
Patent Literature 3 discloses an elevator control device 300 as shown in FIG. 11. The elevator control device 300 has a structure for cooling not a small heat generating component mounted on a circuit board but a large heat generating component 303 such as a high power switching element to which a power cable, etc.
are connected. That is, in the control device 300, a heat sink 302 having a plurality of fins is disposed on an inner surface of a housing 301 so as to form a flow passage along the inner surface of the housing 301, and the flow passage is connected to a fan 304 with a duct 305. The heat generating component 303 is attached directly to the heat sink 302.